川东南官渡下沙溪庙组储层AVO正演模拟研究
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摘要
官渡地区位于四川盆地川南低褶带南缘赤水地区东部,处于川东高陡褶皱带向南帚状延伸与川南恒坝东西向构造带的复合叠加区内。自20世纪70年代初开始油气勘探以来,该区先后有多口井见工业气流和油气显示。
在该地区已进行过关于AVO方面的初步研究工作,包括对AVO角道集的正演模拟,对角道集的正演结果的梯度分析,以及在CMP道集上的角道集分选及AVO拟合分析等。虽然已针对研究区做了一些有关AVO方面的研究工作,也进行了储层预测方面的深入研究,但由于储层的复杂性和技术手段的制约,没有形成统一的地质认识,还未真正形成一套有针对性的有效储层预测、识别评价技术方法。在本地区也未进行AVO方法技术的成功应用,因此需要建立一种适用于该地区含气砂岩的AVO特征,提出本地区AVO应用的使用条件和开展AVO应用的可行性。
地震勘探是世界范围内寻找油气藏的主要方法,而地震反射波振幅与炮检距的关系(Amplitude versus Offset)又是地震勘探中预测油气非常有效的一项新的地震勘探技术,它主要是在叠前道集上分析振幅随炮检距变化的规律,以求岩石的弹性参数、分辨岩性及孔隙充填物,是直接寻找有用矿藏(气藏、盐藏等)的一种新方法。
AVO技术的基础是Zoeppritz精确方程及其近似公式。根据Zoeppritz方程及其近似公式可以得到反映特定地质模型AVO特征的反射系数曲线,这些反射系数曲线将是AVO正演研究的重要对象。正演研究在AVO技术中占有非常重要的位置,通过对AVO正演的研究,可以建立本地区的地层组合和典型含油气地层的AVO特征,有利于AVO资料的处理和解释工作;利用AVO反演提取地层参数的工作同样要用到AVO正演技术,根据地质模型快速有效的生成AVO特征图集将有利于整个研究和勘探工作。
本文首先介绍了AVO技术在国内外的研究现状和研究意义、AVO技术的地球物理原理和岩石物理基础、Zoeppritz精确方程及其近似公式,在此基础上建立模型分析不同参数差异对Zoeppritz近似解及拟合Zoeppritz精确方程的程度的影响,研究了不同参数的变化对反射系数曲线形态的影响,在此项研究的基础上,构建了水平层状模型射线追踪正演合成地震记录,动校正、抽道集等处理后,选用合适的近似方程进行了AVO属性参数的反演,得到模型的P剖面、G剖面、PG剖面、P+G剖面、P-G剖面、sgn(P)G剖面等。随后,依据川东南测井资料构建了实际二维模型,用射线追踪生成正演记录并进行了AVO属性参数的反演处理,对结果进行了对比分析,并针对该区地震地质条件,对在该工区开展AVO资料采集、处理、解释和应用AVO技术的可行性进行了分析,并提出了初步建议。
在进行了AVO正演模拟研究后,利用射线追踪得到的地震记录的基础上,结合实际地震剖面,进行了属性参数的提取,即提取了主振幅、主频率、三瞬参数等属性参数,验证了AVO正演模拟的研究结果。并对在川东南官渡下沙溪庙组储层开展AVO应用的可行性进行了分析和讨论。
Guandu district is located in the eastern part of chishui area which is located in the southern edge of low plait belt of the southern sichuan basin, in the composite superimposition area between the facing south broom shape extensions of the eastern sichuan high and steep fold belt and the constant dam in southern sichuan east-west structural belt. Since the start of oil and gas exploration in the early 1970s, many wells already have industrial airflow and oil & gas display.
At present, a few achievements about AVO have been acquired in the region, including the forward modeling in AVO angle trace gathers, and the gradient analysis on the modeling results of angle gather data, and angle trace gathers sorting and AVO fitting analysis in the CMP trace gathers obtained by conventional seismic data processing. Although many scholars have done a lot of work about AVO aimed at the target area, by now, there has yet to form a set of special technical methods on the effective reservoir prediction and identification, due to the complexity of reservoir and the restriction of technology. And AVO techniques have not been used successfully in this region, so now needs to establish the AVO curve characteristics atlas and the AVO section characteristies atlas, which apply to the sandstone in this region.
The main method of searching for gas and oil is seismic exploration around the world. Making use of amplitude versus offset to search for gas and oil is a new seismic exploration technology, which developed in recent ten years, it mainly analysed the amplitude versus offset rule in pre-stack trace gathers, in order to seek the elastic parameters of rock、distinguish lithology and pore fillings, and that was a new method of finding useful mineral deposits (gas reservoir, underlying salt, etc.).
The technology of AVO is based on Zoeppritz precise equation and its approximate formulas. According to the Zoeppritz precise equation and its approximate formula, we could get the reflection coefficient curve which can reflect the AVO characteristic of particular geological model, and the curve would be the important object in the study of AVO modeling. Modeling study played a very important role in AVO technology. According to the research on AVO modeling, we could bulid the AVO atlas of characteristics about the regional stratigraphic combination and typical petroleum formation, which is in favor of the AVO data processing and interpretation; the extraction of formation parameters also used AVO modeling technique, generating atlas of characteristics quickly and effectively according to geological model would help the whole research and exploration.
This paper firstly introduced the current research status and research significance of AVO technology, then introduced the basic physical theory of AVO technology, rock physical basis, Zoeppritz precise equation and the approximate formulas. On the basis of above-mentioned, building a suitable model to study how different differences of different parameters can affect the accuracy of the Zoeppritz approximation equations, and then studied the effect of variation of different parameters on the reflection coefficient curve. Based on this study, building a suitable horizontal layer model and generated seismic record using ray tracing and apply NMO, sorting CDP gather etc, in the above after work, selected a suitable approximation equation to do AVO property parameters inversion and obtained P section, G section, PG section, P+G section, P-G section, sgn(P)G profile, etc. Then, using the actual logging data to construct the two-dimensional model, generated seismic record using ray tracing and completed AVO property parameters inversion, contrasted and analysed the results, and according to the area seismic geological conditions, analyzed on AVO data acquisition, processing, interpretation and the feasibility of application AVO in this area, and put forward some suggestions.
After researched the AVO forward modeling, on the basis of generated seismic record using ray tracing, combined with the practical seismic profile, completed the extraction of property parameters, obtained the main amplitude, the main frequency, three transient parameters, and so on, and the parameters of the above verify the results of AVO forward modeling. And the feasibility of AVO application are analyzed and discussed.
在该地区已进行过关于AVO方面的初步研究工作,包括对AVO角道集的正演模拟,对角道集的正演结果的梯度分析,以及在CMP道集上的角道集分选及AVO拟合分析等。虽然已针对研究区做了一些有关AVO方面的研究工作,也进行了储层预测方面的深入研究,但由于储层的复杂性和技术手段的制约,没有形成统一的地质认识,还未真正形成一套有针对性的有效储层预测、识别评价技术方法。在本地区也未进行AVO方法技术的成功应用,因此需要建立一种适用于该地区含气砂岩的AVO特征,提出本地区AVO应用的使用条件和开展AVO应用的可行性。
地震勘探是世界范围内寻找油气藏的主要方法,而地震反射波振幅与炮检距的关系(Amplitude versus Offset)又是地震勘探中预测油气非常有效的一项新的地震勘探技术,它主要是在叠前道集上分析振幅随炮检距变化的规律,以求岩石的弹性参数、分辨岩性及孔隙充填物,是直接寻找有用矿藏(气藏、盐藏等)的一种新方法。
AVO技术的基础是Zoeppritz精确方程及其近似公式。根据Zoeppritz方程及其近似公式可以得到反映特定地质模型AVO特征的反射系数曲线,这些反射系数曲线将是AVO正演研究的重要对象。正演研究在AVO技术中占有非常重要的位置,通过对AVO正演的研究,可以建立本地区的地层组合和典型含油气地层的AVO特征,有利于AVO资料的处理和解释工作;利用AVO反演提取地层参数的工作同样要用到AVO正演技术,根据地质模型快速有效的生成AVO特征图集将有利于整个研究和勘探工作。
本文首先介绍了AVO技术在国内外的研究现状和研究意义、AVO技术的地球物理原理和岩石物理基础、Zoeppritz精确方程及其近似公式,在此基础上建立模型分析不同参数差异对Zoeppritz近似解及拟合Zoeppritz精确方程的程度的影响,研究了不同参数的变化对反射系数曲线形态的影响,在此项研究的基础上,构建了水平层状模型射线追踪正演合成地震记录,动校正、抽道集等处理后,选用合适的近似方程进行了AVO属性参数的反演,得到模型的P剖面、G剖面、PG剖面、P+G剖面、P-G剖面、sgn(P)G剖面等。随后,依据川东南测井资料构建了实际二维模型,用射线追踪生成正演记录并进行了AVO属性参数的反演处理,对结果进行了对比分析,并针对该区地震地质条件,对在该工区开展AVO资料采集、处理、解释和应用AVO技术的可行性进行了分析,并提出了初步建议。
在进行了AVO正演模拟研究后,利用射线追踪得到的地震记录的基础上,结合实际地震剖面,进行了属性参数的提取,即提取了主振幅、主频率、三瞬参数等属性参数,验证了AVO正演模拟的研究结果。并对在川东南官渡下沙溪庙组储层开展AVO应用的可行性进行了分析和讨论。
Guandu district is located in the eastern part of chishui area which is located in the southern edge of low plait belt of the southern sichuan basin, in the composite superimposition area between the facing south broom shape extensions of the eastern sichuan high and steep fold belt and the constant dam in southern sichuan east-west structural belt. Since the start of oil and gas exploration in the early 1970s, many wells already have industrial airflow and oil & gas display.
At present, a few achievements about AVO have been acquired in the region, including the forward modeling in AVO angle trace gathers, and the gradient analysis on the modeling results of angle gather data, and angle trace gathers sorting and AVO fitting analysis in the CMP trace gathers obtained by conventional seismic data processing. Although many scholars have done a lot of work about AVO aimed at the target area, by now, there has yet to form a set of special technical methods on the effective reservoir prediction and identification, due to the complexity of reservoir and the restriction of technology. And AVO techniques have not been used successfully in this region, so now needs to establish the AVO curve characteristics atlas and the AVO section characteristies atlas, which apply to the sandstone in this region.
The main method of searching for gas and oil is seismic exploration around the world. Making use of amplitude versus offset to search for gas and oil is a new seismic exploration technology, which developed in recent ten years, it mainly analysed the amplitude versus offset rule in pre-stack trace gathers, in order to seek the elastic parameters of rock、distinguish lithology and pore fillings, and that was a new method of finding useful mineral deposits (gas reservoir, underlying salt, etc.).
The technology of AVO is based on Zoeppritz precise equation and its approximate formulas. According to the Zoeppritz precise equation and its approximate formula, we could get the reflection coefficient curve which can reflect the AVO characteristic of particular geological model, and the curve would be the important object in the study of AVO modeling. Modeling study played a very important role in AVO technology. According to the research on AVO modeling, we could bulid the AVO atlas of characteristics about the regional stratigraphic combination and typical petroleum formation, which is in favor of the AVO data processing and interpretation; the extraction of formation parameters also used AVO modeling technique, generating atlas of characteristics quickly and effectively according to geological model would help the whole research and exploration.
This paper firstly introduced the current research status and research significance of AVO technology, then introduced the basic physical theory of AVO technology, rock physical basis, Zoeppritz precise equation and the approximate formulas. On the basis of above-mentioned, building a suitable model to study how different differences of different parameters can affect the accuracy of the Zoeppritz approximation equations, and then studied the effect of variation of different parameters on the reflection coefficient curve. Based on this study, building a suitable horizontal layer model and generated seismic record using ray tracing and apply NMO, sorting CDP gather etc, in the above after work, selected a suitable approximation equation to do AVO property parameters inversion and obtained P section, G section, PG section, P+G section, P-G section, sgn(P)G profile, etc. Then, using the actual logging data to construct the two-dimensional model, generated seismic record using ray tracing and completed AVO property parameters inversion, contrasted and analysed the results, and according to the area seismic geological conditions, analyzed on AVO data acquisition, processing, interpretation and the feasibility of application AVO in this area, and put forward some suggestions.
After researched the AVO forward modeling, on the basis of generated seismic record using ray tracing, combined with the practical seismic profile, completed the extraction of property parameters, obtained the main amplitude, the main frequency, three transient parameters, and so on, and the parameters of the above verify the results of AVO forward modeling. And the feasibility of AVO application are analyzed and discussed.
引文
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[2]Aki, K. I., and Richards, P. G., Quantitative seismology[M]: W. H. Freeman and Co,1980.
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[6]Li Yongyi , Jonathan D. The applications of amplitude versus offset in carbonate reservoirs: renexamining the potential[C]. SEG 70th Annual Meeting Expanded Abstracts. Calgary, 2000.
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[14]田亚铭,施泽进,王长城,等.官渡构造带下沙溪庙组砂体展布特征研究[J].石油物探,2008,47(3):213-214.
[15]刘伟,曹思远. AVO技术新进展[J].物探化探计算技术,2008,30(6):471-472.
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[2]Aki, K. I., and Richards, P. G., Quantitative seismology[M]: W. H. Freeman and Co,1980.
[3]Koefoed. On the Effect of Poissin’s Ratios of Rock Strate on the Reflection Coefficients of Plane Wave[J]. Geophysical Prospecting, 1955, 3(4):381-387.
[4]Bortfeld,R.Approximation to the reflection and transmission coefficients Of plane longitudinal and transverse wave[J].Geophy-sics Prospecting,1961,9(4):485-502.
[5]Shuey. A simplification of the zoeppritz equations. Geophysics ,1984 ,50 :609-634.
[6]Li Yongyi , Jonathan D. The applications of amplitude versus offset in carbonate reservoirs: renexamining the potential[C]. SEG 70th Annual Meeting Expanded Abstracts. Calgary, 2000.
[7]殷八斤,等. AVO技术的理论与实践[M],北京:石油工业出版社,1995.
[8]陆基孟.地震勘探原理[M].东营:石油大学出版社,1993.
[9]禾苗.川东南赤水区块储层预测研究[D].成都:成都理工大学,2010.
[10]韩虹. ZZ地区下沙溪庙组有利储层预测研究[D].成都:成都理工大学,2009.
[11]覃思.煤层气AVO研究与应用[D].成都:成都理工大学,2008.
[12]王栋.AVO分析与流体识别[D].成都:成都理工大学,2009.
[13]宋建国,王艳香,乔玉雷,等. AVO技术进展[J].地球物理学进展,2008,23(2):508-510.
[14]田亚铭,施泽进,王长城,等.官渡构造带下沙溪庙组砂体展布特征研究[J].石油物探,2008,47(3):213-214.
[15]刘伟,曹思远. AVO技术新进展[J].物探化探计算技术,2008,30(6):471-472.
[16]彭晓波,严丽萍,张庆堂,等.AVO油气勘探技术[J].油气田地面工程,2010,29(2):67-68.
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